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Relicts are natural ecological laboratories

By Dave Armstrong - 13 Aug 2014 6:11:0 GMT
Relicts are natural ecological laboratories

Did the Ozark Mountains once look like this? The prickly pear seems to indicate that cacti, perhaps even the great Carnegiea gigantea here in the Sonoran desert, near Scottsdale, dominated in a desert climate; Scottsdale image; Credit: © Shutterstock

Scott A. Woolbright and four colleagues from the University of Illinois, Northern Arizona University and the University of Tennessee are ecologists par excellence. Instead of mulling about in forests and streams, they have recognised that isolated pieces of landscape hold the habitats of long-gone communities in many places worldwide. They published a most interesting paper this week in Trends in Ecology and Evolution as- Climate relicts and their associated communities as natural ecology and evolution laboratories.

These habitat islands have been called natural laboratories, in which evolution of a species can be worked out as well as ecological patterns in a whole, but small community. Long-term climate change can't be easily replicated, but the genomes of species in these relict communities hold this information.

Climate drives change in every organism that is recorded in genetic form. The species interact within their community, playing an important role in their joint survival. If this reminds you of Conan Doyle's Roraima, the Lost World is very relevant, in places such as - The Lost World of Australia.

If one of the relic species goes missing, the others could well display the effect of their extinction, or simply die off. The threats over millennia to communities like these have been more than just climate. Invasions from adjacent communities obviously take place and humans are probably now destroying many of these precious flashbacks to the distant past.

So where do these interesting locations show up? In North America, the Pike Lake stickleback originated, according to glaciation experts, in the Champlain Sea of Ontario which, after the weight of the ice was removed, left salty remnants of which Pike Lake is one. Climate has also forced isolation as the equatorial regions heat up. Organisms move to higher altitude in many cases, which means they're stranded when the rest of the population dies out on lower warmer slopes.

Genetically, these new entities may be simple varieties or complete new species. The mountain gorilla is an example of a species that we all know is limited to the tops of mountains in Uganda and the DRC. We need to add the whole community of food plants, associated insects and even bird and other species associated with gorillas to build up the whole concept of a habitat island.

We are safer with some of the studied North American climate relict sites, such as places studied by Scott Woolbright in the Ozarks. Well drained and rocky substrate there creates a glade ecosystem where sloping ground can encourage the growth of prickly pear cacti and other desert and prairie species such as the collared lizard, Crotaphytus that last covered the whole area around 7,000 years ago in the Hypsithermal Interval, during the Holocene Period, when warming dried out much of the glacial Northern Hemisphere.

The area now is rich in oak and hickory forest, encouraged by more warming during the last 2,000 years, but then, Opuntia species were part of the dominant desert plant community. With a lot more information, we can soon gain views of what the planet looked like in many different regions and how animals and plants once roamed in places we never believed possible.